This invention generally relates to a support post for use with a dental implant and adapted to support a prosthesis thereon. Specifically, the support post is comprised of a ceramic portion and a metal portion.
Surgical techniques for support of dental prostheses by means of metallic bone-embedded artificial root fixtures are well known. According to one prior art technique, a titanium bone-embedded implant fixture is interfaced with a metallic abutment post on which a superstructure, such as a prosthesis, is supported. The post has an internally shouldered access bore through which a screw is inserted to hold the implant and the post assembled. A number of problems and restrictions are presented, however, in the attachment and retention of the superstructures to such abutment posts.
Specifically, the typical superstructures for use with such posts are made of porcelain. The use of a titanium post generally results in a dark, central rod-like shadow, particularly when exposed to bright light, which makes the prosthesis somewhat unattractive since it is distinguishable from a natural tooth. Further, since the materials are different, sometimes there are problems with securing the prosthesis to the support post.
One attempt to solve the attractiveness and securement problems involves making a support post entirely of ceramic material, specifically, aluminum oxide. This approach allows direct surface bonding by interaction of a porcelain coping and/or prosthesis to the support post, resulting in a secure and almost seamless bond between the prosthesis and support post. While presenting an alternative attraction to the use of a titanium support post, the proposed solution presents a number of problems.
Ceramic materials generally have a much greater hardness than titanium. When a ceramic support post is used, inevitable rocking of the support post due to, for example, chewing, causes a high stress interaction between the metal implant and the ceramic material of the post. Since a ceramic support post is of greater hardness than a titanium implant, it can and does cause damage to the implant. If sufficient damage is caused, eventual surgical intervention is required to remove and replace the titanium implant. In addition, ceramic material is typically not radiopaque. Thus, when examining the juncture between the support post and the titanium implant through conventional dental x-ray imaging, the interface between the two elements is not readily viewable and, thus, adequate x-ray examination cannot be conducted.
The present invention is a support post for use with a dental implant. The support post comprises a ceramic portion, a screw, and a metal portion. The ceramic portion is adapted to support a prosthesis thereon. The ceramic portion has a supragingival region for protruding beyond the gingiva and a subgingival end for extending into the gingiva. The ceramic portion has a passageway extending therethrough. According to one embodiment of the present invention, the passageway narrows to form a shoulder that is made entirely of ceramic.
The screw is adapted to engage threads of an internally threaded bore in the implant and be insertable through the passageway. The screw comprises a head and a threaded section. The head of the screw seats entirely on the shoulder.
The metal portion comprises a lower section and an upper section extending into the passageway. The metal portion abuts the subgingival end of the ceramic portion. The lower section is adapted to receive and engage a corresponding boss of the dental implant. The metal portion has an opening to provide access to the screw.